Our primary objectives are to produce new data on tone in aphasia and, at the same time, address theoretical issues concerning hemispheric specialization for tone and the nature of dysprosody in Broca's aphasia. Two experimental phonetic investigations are proposed. The purpose of the first study is to determine the extent and nature of impairment in the production of tones by Thai-speaking aphasics. Thirteen subjects will provide the data for this study including 5 normal and 8 brain-damaged (2 Broca's, 1 transcortical motor, 1 global, 1 conduction, 1 Wernicke's, 1 dysarthric, and 1 right brain-damaged) native speakers of Thai. The purpose of the second study is to determine the extent to which the control of FO and timing may be selectively impaired depending upon the size of the linguistic planning unit in the speech of a single Thai-speaking Broca's aphasic. Both studies will employ computerized techniques of acoustical analysis of FO and timing. The long-term objectives of this research program are (1) to provide a detailed, aoustical description of FO and timing patterns in spontaneous and read speech of Thai-speaking aphasics, as well as other brain-damaged populations, and (2) to show how both normal and abnormal FO and timing patterns can give insight into the nature of language deficits that follow from damage to the brain. The studies represent a first step toward the attainment of these long term goals. Such detailed descriptions of the breakdown of prosodic elements in aphasia are essential for accurate clinical assessment and remediation of dysprosody in aphasic patients.